Method for heat-setting of crimps of artificial filament tows

ABSTRACT

The present invention provides a method of producing excellent crimped fibers, in which artificial fibers are subjected to mechanical crimping, enveloped in a crimped state in a wrapping under tension, and are passed through a high temperature pressurized saturated steam chamber at the annealing temperature of the fibers. The crimps are permanently fixed by the effect of moisture and heat under a lateral pressure. The resulting fibers, when made into an end product, have a high degree of crimp recovery upon reheating in the finishing process, even if the crimps have been straightened by processing in air before finishing operation.

United States Patent [151 3,667,094 Yazawa 1 June 6, 1972 [54] METHODFOR HEAT-SETTING 0F 3,644,145 7/1962 Tager et al ..28/l.6

CRIMPS 0F ARTIFICIAL FILAMENT 3,389,445 6/1968 Schreffler 3,408,7131/1968 Parker ct al. ..28/l.6

TOWS

[72] Inventor: Masnhidl: Yuzawa. 'loyku. Japan [73] Assignee: PolymerProcessing Research Institute Ltd., Tokyo, Japan [22] Filed: May 27,1970 [2]] App]. No.: 40,795

[52] US. Cl.. ..28/72.l4

[51] Int. Cl ..D02g 1/12 [58] Field ofSearch ..28/1.6, 1.7, 72.14

[56] References Cited UNITED STATES PATENTS 2,997,747 8/1961 Russo et a]..28/1.6 3,000,059 9/1961 Russo et a] ..28/l.7 X

Primary Examiner-lmuis K. Rimrodt Attorney-James E. Armstrong and RonaldS. Cornell ABSTRACT finishing process, even if the crimps have beenstraightened by 7 processing in air before finishing operation.

5 Clains, 5 Drawing Figures PATENTEDJUN 6 I972 SHEET 10F 3 FIG.

FIG. lb

PATENTEBJun 6 I972 SHEEI 2 BF 3 FIG. 3

PA'TENTEDJun 6 I972 SHEET 30F 3 FIG. 4

METHOD FOR HEAT-SETTING OF CRIMPS OF ARTIFICIAL FILAMENT TOWS BACKGROUNDOF THE INVENTION Filament tows or yarns of artificial fibers made ofvarious kinds of polymers are now on the market. The heat resistanceafter these polymers have been formed into fibers varies according tothe kind of polymer. In general, filament tows or yarns of artificialfibers are frequently subjected to a heat treatment or an annealingprocess in order to make the quality unifonn and to improve the heatresistance. However, in the case of regenerated cellulose fibers, evenin the case of heating in the presence of water, which serves to swellthe fibers, it is necessary to perform a saturated steam treatment at ahigh temperature of 180 to 200 C. and a high pressure of 9 to 14 kg/cmgage pressure with 25 to 40 percent by weight water, based on the weightof the fibers. Since the atmosphere of the heating chamber is saturatedsteam containing substantially no non-condensible gases, thepressuredeveloped within the chamber will depend upon the temperature to whichthe filament tow is heated. (Reference: Japanese Pat. No. 474,880,publication No. 319/Showa 41.) The products on the market are generallythose that have not undergone such a heat treatment or annealingprocess.

From the practical point of view, the highest temperature at whichdeterioration of the fibers caused by relaxation in molecularorientation at a given treatment temperature is negligible, isfrequently called the heat resistance temperature of the fibers. Theheat resistance of fibers of synthetic polymers in general differs tosome extent according to the type of polymer, average degree ofpolymerization, degree of molecular orientation, temperature and time ofthe treatment, or whether or not the fiber has undergone a heattreatment. The heat resistance temperature is accepted as the optimumannealing temperature of the fiber.

For example, the heat resistance temperature for polyvinyl chloridefibers ranges from 1 to 1 C., and for modacryl fibers of 60 percentvinylchloride and 40 percent acrylonitrile, from 120 to 125 C. As foracrylic fibers containing more than 85 percent acrylonitrilecopolymerized with another comonomer, the heat resistance decreases asthe content of the comonomer increases. Thus, most acrylics on themarket generally contain 5 to 7 percent comonomer, and their heatresistance in the presence of water is generally between 130 to 140 C. A100 percent acrylonitrile polymer has a heat resistance of 160 to 180 C.even in the presence of water, and when dry it can be decomposed andcarbonized without causing substantial relaxation of molecularorientation.

' The highest heat resistance in water of polyvinyl alcohol fiber evenafter heat treatment is about 100 C., and the heattreated fiber evenafter acetalization with formaldehyde shows a heat resistance in waterof about 120 C. However, in a dry state it has a heat resistance of 210to 220 C., whether or not it has been treated with formaldehyde.

The heat resistance of a copolymer fiber consisting of 85 percentvinylidene chloride and 15 percent vinyl chloride lies between 100 to 115 C.

The heat resistance of polyamide fibers differs according to theircomposition. For Nylon 6 it is from about 130 to 150 C. in the presenceof water and about 180 to 190 C. in dry heat. The heat resistance ofNylon 66 is about 15 to C. higher than that of Nylon 6.

The heat resistance of polyethylene terephthalate fiber in the presenceof water is about 160 C. and 175 to 200 C., in dry heat, that of highdensity polyethylene fiber is 120 to 125 C., and that of polypropylenefiber is 145 to 150 C. As for these olefinic fibers, no differencebetween the heat resistance in the dry and wet states is observed.

It is impossible to heat-set a mass of fibers evenly in a short periodof time by a dry heat method whether it is done by dry hot air or bycontact conduction with a heated surface. Disadvantages of the dry heatmethod are well known in the literature. Dry hot air, moreover,oftencauses oxidation of fibers,

and dyed fibers change colors at high temperatures. Up to this time, thedry heat method is only used in heat setting of twists of undyed finefilament yarns.

For a tow of several hundred thousand denier, crimping of polyesterfibers is carried out only by the stufi'er box method with steam up toC. Continuous heat setting of fiber crimps by means of steam at a hightemperature and pressure has never been performed. As for crimp settingof acrylic fibers, the tow is crimped in a stufier box, and about 50 to100 kg of the crimped tow, gathered in mass, are heat-treated withsaturated steam in a batch-type autoclave. In this process, if the towis packed so tightly as to press each fiber fimily, the steam cannotpenetrate into the core of the fiber mass, and thus it is not evenlyheated. In addition, if the fibers are not subjected to heat treatmentin order to be contracted 20 to 23 percent of the length, they do notbecome fibers of practical use, because of low knot strength andsusceptibility to fibrillation. In practical operation, however, theyare stufl'ed loosely in the autoclave so as to have as low a density aspossible to allow contraction. Further, they are heat-treated withrepeated treatments applying vacuum followed by steaming, and thepractical temperature for the heat treatment is often lower than theoptimum temperature by 5. to 8 C., as explained hereinunder in details.

Since a part of the crimps are not pressed by' some means or others, thestrain once given at the time of crimping returns by heat to theprevious non-crimped state. This kind of phenomenon is well-known asplastic memory". The crimps of fibers in the lower part remain as theyare, due to the pressure imposed upon them by the weight of fibers fromthe upper part. However, since the buckled parts of the fibers in theupper part of the mass are not pressed firmly, the crimps are apt to bestraightened and their molecular orientatini is not rearranged,resulting in the failure of firm fixation of crimped state. Accordingly,for crimp setting, the process mentioned above, is inadequate. Since thefibers at the bottom of the autoclave are pressed by the weight fromabove, the relax annealing of 20 to 23 percent contraction is not ableto occur. The fibers at the upper part are, however, free enough forcontraction, but the crimp setting is insufficient. As the fibers at thebottom are not free for contraction, the crimpsetting may become betterto some degree after a sufficiently high temperature heat treatment. Butunder these conditions due to the difference of contraction in yariouslayers of fibers, variation in physical properties and unevenness indyeing occur. Accordingly, although a temperature about 135 C. is theoptimum temperature for heat treatment of acrylic fibers, as a practicalprocedure, heat treatment at the less desirable temperature of to 128 C.is used. Thus, the greatest disadvantages of acrylic fibers that aresubjected to batch-type autoclave heat treatment are unevenness incontraction and unevenness in quality caused by heating of the fibers attemperatures insufi'icient for optimum heat treating, namely, crimpsetting.

SUMll/IARY OF THE INVENTION The present invention provides a method ofheat setting of crimps, wherein crimps are applied to fibers gathered ina tow form including a tow and yarns gathered in a tow form (hereinunderdenoted as a tow for simplicity) mechanically, for example by means of astufier box before or after a bleaching or dyeing process, and the towis thereafter introduced into a heating chamber of saturated steamwherein the tow is permanently crimped. Before introducing into aheating chamber the tow is enveloped in a wrapping in a tapered guideconduit, the tow being fed in excess to the wrapping so that the tow mayhave crimps at least to an extent corresponding to the crimping ratio ofthe tow plus the shrinkage of the tow during subsequent heat treatment.During the wrapping operation the tow is increased in density by thetapering of the conduit, the outlet of which is substantially ellipticalin shape. The tow is then introduced into a pressurized heating chambercontaining saturated steam without substan- "tially any non-condensiblegases and heated at the heat resistance temperature of the fibers, thetemperature of which differs according to the particular fibers aspreviously explained. In the heating chamber a lateral pressure isapplied to the tow by the tension of the wrapping; by sliding thewrapped tow over fixed bars or curved surfaces arranged in the heatingchamber; by changing the running direction of the tow on rollers; bypressing the tow between rollers; or by a suitable combination of thesemeans. While under tension the tow is subjected to moisture at a hightemperature and pressure to set the bends and crimps by heat, and isdrawn out into the atmosphere where the crimped tow is separated fromthe wrapping. The tow is subsequently processed and the wrapping isreused as required. The heat-fixed crimps of the treated filament toware stable and durable, possessing an excellent crimp recovery uponreheating even if the crimps are straightened during subsequentprocessing.

DETAILED DESCRIPTION I In order to set crimps, it is necessary torearrange the molecules so that the distorted molecular orientation atthe buckled parts of the crimped fibers can be stabilized in the buckledstate. If a sufficiently strong lateral pressure is not applied to thecrimps, even if they are heated at a high temperature, the crimps areapt to vanish, remain unstable and are not firmly fixed. Moreover, ifsuch crimps are straightened in subsequent processing, the degree ofcrimp recovery is low.

Use of high pressure steam at a high temperature lowers the optimumtreating temperature by 20 to 50 C. in comparison with that required indry heat process, because the moisture serves as a softening agent orplasticizer for fibers that have a certain hydrophylic property. Thus,saturated steam is an ideal heating medium for fibers because itfacilitates even heating in a short period of time at a lower processingtemperature.

In this invention the crimped parts of the fibers are sub jected to asufficiently strong lateralpressure and fibers in the form of a thicktow are passed continuously into a heating chamber of saturated steam ata high pressure and a high temperature. At this time, the softeningpoint and the treating temperature for the fibers in most cases arelowered by moisture because it acts as a softening agent. The method ofthis invention enables a continuous and uniform processing operation inwhich the treating temperature used is higher by about C. than that ofthe conventional batch-type autoclave method. Also, according to the newmethod, the required treating period is less than 60 seconds, includingheating up time of the wrapped tow. The resulting products are ofuniform physical properties because of the perfect crimp settingresulting from uniform heat treatment at a uniform temperature. Acharacteristic of this invention consists in its ideal practice ofpermanent crimp setting, because an ideal even heat treatment is onlypossible when it is done within the range of i 1 to 2 C. of the optimumtemperature, namely, the heat resistance temperature of the particularfiber being treated so far as the other conditions, such as the lateralpressure imposed upon fibers, are maintained almost constant throughoutthe whole length of the tow.

When a crimped tow, enveloped in and guided by a wrapping under tension,travels a zigzag course on fixed bars in the pressurized heatingchamber, the tension of the wrapping lying on the outer side of thewrapped tow becomes greater than that of the inner one which contactswith the bars. Thus the fibers enveloped in the wrapping receive alateral pressure from the outside wrapping and are pressed onto thebars. Similar phenomenon is seen, when the wrapped tow changes itsrunning course on a roller. In this case, the lateral pressure increasesas the difference in tension and the pulling tension imposed uponwrappings for passing through the heating chamber increase, and when itturns along rollers or bars, or it is passed between rollers, thelateral pressure is evenly applied to each fiber. It is possible withthis invention to attain the molecular re-orientation at the buckledparts of the fibers, because it is possible to apply an outer lateralpressure to the crimped parts of enveloped fibers through the wrappingusing at the same time the plasticizing effect of pressurized steam atthe optimum temperature. Thus, pemtanent fixation of mechanically givencrimps has been achieved for the first time with this invention. Sincefibers pass continuously in fon'n of a tow in saturated steam at theoptimum temperature, the period of time required to heat evenly throughto the core of the tow is only about 20 to seconds. Comparing this withthe batch-type autoclave method in which one operation period requiresmore than 30 minutes (with repetition of steps: evacuation pressurizedsteam charge evacuation pressurized steam charge evacuation etc.excluding the time for charging and discharging the tow, the method ofthis invention provides much greater speed and efficiency, and therequired apparatus can be made in amore compact form and at a lowercost.

BRIEF DESCRIPTION, OF THE DRAWINGS In FIG. 1a is shown a series ofapparatus, in which a filament tow which has been spread in flat to havealmost an uniform thickness is passed through a steam chamber atatmospheric pressure, and is crimped by means of a stuffer box. Thecrimped tow of controlled crimping is sent into a tapered guide conduit,through which'a wrapping to envelop the tow passes under a tension.While the tow is being enveloped by the wrapping, the density of thefilament tow is increased at the outlet side of the conduit.

In FIG. 1b is shown the manner in which the crimped tow is enveloped tothe extent of 1% times of its circumference by the wrapping, which ismaintained under tension, and folded in U-shape for easy passing throughpressure seals shown in FIG. 2 and FIG. 4.

In FIG. 2 is shown an apparatus, in which the wrapped tow is introducedinto a high temperature pressurized saturated steam chamber through anarrow valve-controlled pipe at the inlet side. The tow is shiftedsideways on rollers having axes which incline to each other as shown inFIG. 3, while enveloped by the wrapping under tension. The'tow issubjected to a strong lateral pressure from the roller surfaces, whileit changes its direction, and it is drawn out into the air through anarrow pipe having multiple valves.

In FIG. 4 is shown an apparatus for the practice of this invention, inwhich the wrapped tow under tension runs continuously over the surfacesof rollers which are positioned and arranged in a heating chamber. T

DETAILED DESCRIPTIGN OF THE DRAWINGS In FIG. 1a an uncrimped tow 1passes between the first pinch rollers 2, 2', and over guide bar 3, andis fed vertically into steam chamber 4 at a temperature of approximatelyC. under tension by which the tow may be stretched as much as 3 to 5percent between the first pinch rollers 2, 2' and the second pinchrollers 5, 5', while care-is taken so that condensed water does notcontact with the tow. The tow is then passed between guide rollers 6, 7,and 8 and then passes pinch rollers 9, 9 and is pressed into stuffer box10, within which it is folded and crimped. Stuffer box 10 is rectangularin section, and is constructed such that its bottomplate can be moved upand down at a predetermined pressure. Crimped tow ll, pushed out fromstufier box 10, is received by .l-shaped slant conduit 12, slides in adownward direction, and is accumulated at the bottom of the conduit.Even if the crimped tow is pushed out inconstantly at an indefinitespeed, the accumulated tow at the bottom of conduit 12 serves as abuffer zone and provides a constant speed supply for subsequentprocessing. The crimped tow is pulled by the travel of the wrapping,passes over guide bar 13, and while it passes through tapered guideconduit 14 for' application of the wrappings, it is shaped so that bothsideends of the wrapping are overlapped like the front side of aJapanese kimono,as

shown in of FIG. 1b in which the tow is enveloped in the wrapping to theextent of one and a half times. At this time wrapping 15 is subjected totension by the difference of peripheral speeds between pinch rollers 16,16 and 17, 17'. In addition, the guide conduit 14 tapers into a smallsection at its outlet so the crimped tow is tightly enveloped in thewrapping. When it is necessary to supply more crimped tow into thewrapping, it is possible with the use of tongue-shaped blade 18 havingprojected parts (not shown) on its lower side which push the tow forwardby frictional contact with the fiber during forward travel of the bladeand slide over the fibers on return travel. By regulating the amplitudeand the number of reciprocating motion of the blade, a desired increasein supply is possible. Tow 19, enveloped in wrapping 15, is thenintroduced into a pressurized steam chamber through a narrowpressure-sealing tube having a circular or elliptical cross section. Atthis time the tow cannot escape from the wrapping if the overlapped partof the wrapping is bent inwardly as shown in 19, 19' ofFIG. 1b.

FIG. 2 shows a high pressure steam chamber for high temperature crimpsetting of a wrapped fiber bundle. Wrapped fiber bundle 19 is introducedinto saturated steam chamber 23, through pinch rollers 20, 20' andorifice-22 with tapered inlet pipe, the degree of orifice opening beingcontrolled by valve 21.

As shown in FIG. 3 the tow shifts sideways successively on a pair ofdriving rollers 24, 25, the axes of which incline somewhat toward eachother.

After a prescribed period of time of travel in the chamber 23 (in mostcases a period less than 1 minute is sufficient), the tow is drawn outinto the atmosphere by pinch rollers 32, 32 after passing through valves26, 27 and 28 which are attached to pressure-sealing narrow pipe 31 atthe outlet side. Narrow side pipes 29 and 30, each having a valve, areprovided to leak steam directly into the air. This steam pressuresealing method and apparatus are described in my other patents (U.S.Pat. Nos. 2,954,687 and 3,213,470). For purposes ofthis invention thepressure-sealing method is not limited to the above one; thus any othersuitable pressure sealing method may be used. Another effective methodto use, for example, is one in which a narrow pipe 50 to 70 cm longhaving a variable cross section, that is, from a circle to an ellipsebecause of the elasticity of the material (for example, apolytetrafluoroethylene pipe laminated with a thin glass fiber fabric,or a thin elastic metal pipe), is held between two metal plates, and thedistance between the plates is adjusted such that the cross section ofthe pipe orifice can be changed.

Steam is supplied through pipe 37, and condensed water is taken outthrough pipe 36 and a trap. Roof 33 may be provided, if necessary, toprevent condensed water from falling on the wrapped tow. Pipe 35 is avent, and the pressure is indicated by gage 34.

When the axes of rollers 24 and have an inclination of a certain angleto each other, traverse shifting of the wrapped tow is satisfactorilyaccomplished as shown in FIG. 3. If there is concern that the tow mayescape from the wrapping due to too great a distance between 24 and 25,guide conduits 38, 38' should be provided to bend the wrapped towoutwardly from the roller with a certain curvature so that theoverlapped part of the wrapping can pass through the conduit by means offrictional contact. Another way of preventing escape of the tow from thewrapping is to provide a number of bars (not shown) on the path of thewrapped tow so that the tow can travel a zigzag course.

FIG. 4 shows an apparatus in which a number of rollers are verticallyarranged, over which the wrapped tow moves successively. The crimps ofcrimped fibers are heat-set while the tow passes over these rollers.Wrapped tow 19 is introduced into pressurized steam chamber 43, passingthrough valve 41 having a tapered inlet guide pipe and through pressuresealing narrow pipe 42, and is fed to externally driven roller 44. Thetow then moves upward, passing between three free rollers 45, 46 and 47moving on bearings in the chamber. The free rollers are light in weightso that the fibers do not stick together and are spaced a little apartfrom each other. The tow then runs onto externally-driven roller 48, andon three light guide rollers 49, 50 and 51 similar to those describedabove. Afterwards it passes over externally driven roller 52, lightguide roller 53 and roller 54, which is spaced at a certain distancefrom roller 53, and which is arranged at an angle with respect to thegroup of rollers 44 to 53 below. The tow changes its way downward andshifts sideways as much as the width of the wrapped tow before it isheld again between rollers 53 and 52. It runs successively downward onthese rollers. When the total number of rollers is an odd number, theoutlet end of the tow comes out at the opposite side from the inlet. Thetow, afier passing through multiple-valved pressure sealing narrow pipe55 at the outlet side, is drawn into the air by pinch rollers 56, 56.Even if a large number of rollers are arranged and operated as describedabove, there is no danger that the wrapped tow may slip from the ends ofrollers, provided that every other roller is fitted with flanges or ribsat the side ends. If the width of a wrapped tow is so wide as not topennit the tow to run doubly on the rollers, several heating chambersconstructed as shown in FIG. 4 may be arranged in series, and the tow,after being heat-treated for a required period of time (in most cases aperiod less than one minute) and passing through the pressure seal, isdrawn out into the air. The wrapped tow, while being drawn out into theair after heat treatment, is separated from the wrapping.

The wrapping used in the invention is generally a product of a woven orknitted fabric, including a net or the like, irrespective of density oftexture, and in form of a thin band or belt having a width sufficient toenvelop within it a tow of crimped fibers of highest possible densityand the preferable width is one and half times wider than the apparentcircumference of the crimped tow to be heat-set. Useful wrappings alsoinclude those of the above type reinforced at both selvages with anarrow tape sewed on it, especially in the case of a net or knittedfabric.

If staple fibers cut from a crimped tow interfere with spinning processbecause of too many crimps, the crimped tow should be stretched betweenrollers while it is passed in a steam chamber at atmospheric pressure sothat the residual crimps do not interfere with the spinning process. Theresidual crimps are temporarily fixed by cooling as they are and the towis cut into fibers of a suitable length for spinning material.

Spun yarns made of the above-described fibers display latent ability torecover crimps applied at the time of setting, when treated with steamor water at to C. in a tention-free state. Accordingly, fabrics of highbulkinees may be obtained. Crimped tows obtained in accordance with thepresent invention, even if the crimps are straightened during towspinning process, show a recovering property of crimps at the time ofsetting, when steamed at a temperature about 100 C. Accordingly,resulting fabrics become those of high bulkiness, when steamed atatmospheric pressure.

The wrapping, after separation from the tow, is returned to the towenveloping device for reuse, after being turned over, spread and ironedon a hot roller to remove wrinkles.

Fibers gathered in a tow form applicable for this invention are not onlyfilament tows or yarns as hereinbefore described, but also spun yarns,fibrillated fiber yarns from uniaxially stretched fiber-formable polymerfilm or other filamentary materials capable of being gathered in a towform.

My invention is further illustrated by the following examples:

EXAMPLE 1 A regenerated cellulose fiber tow of 500,000 deniers was spunby the viscose method. A single filament of the tow was 1.5 deniers, hada strength of 3.5 g/d and an elongation of l5 percent. It was neutral orslightly arnmoniacally alkaline. The

having a bottom plate to which a certain air pressure was applied androllers positioned on the inlet side 100 mm in width and 120 mm indiameter. The crimped tow had an apparent thickness of 800,000 deniers.It was introduced into a tapered guide conduit and was enveloped in acotton cloth, 320 mm in width and 90 g/m in weight as in FIG. 1b, undertension between delivery rollers 16, 16' and drawing rollers 17, 17. Thewrapped tow, after being folded double with the overlapped part in thecenter, was introduced into an autoclave as shown in FIG. 2 to undergostaturated steam treatment for 45 seconds at a gage pressure of kg/cmand was drawn into the air. A part of the crimped tow, when separatedfrom the wrapping, maintained a definite length in water at 100 C. for30 minutes in a straightened state, but after removal of tension, thecrimps recovered almost to the original state, showing very stable andstrong recovery. Wrinkled parts of the wrapping were flattened afierstrong ironing, but when dipped into hot water, they once more becamewrinkled. Thus, when processed according to the invention, wrinkles of acotton cloth were stably fixed, even against ironing.

A major part of the crimps of the tow were straightened under tension ina steam chamber at atmospheric pressure,

temporarily fixed in the straightened state by cooling and then the towwas cut into lengths of 50 mm. Cut fibers were used for blended andunblended spinning. An unblended spun yarn, when steamed at 100 C. in atension-free state, become a high bulky yarn, which showed that themechanically applied crimps were extremely stably fixed,'and the yarnhad high resilience. The Laue spots in the X-ray diffraction photographswere fairly distinct, showing an increase in the crystalline area. Thewater absorption of the raw fibers was 70 to 72 percent" afterdehydration by a certain centrifugal force, but absorption after heattreatment was lowered to 55 percent. This obviously shows a decrease inswelling properties. The wet Youngs modulus in water showed a highvalue. No substantial degradation of the polymer was observed. It wasobserved that the crimped fibers were suitable for blend spinning withsynthetic staple fibers, in place of mercerized cotton.

EXAMPLE 2 An acrylic fiber (Cashimilon: Trade name of acrylic fibermanufactured by 'Asahi Kasei 'Kogyo Co. Ltd. Japan) 5,000,000denier towconsisting of single fibers of 3 deniers was padded to take up 1.3percent-Cathilon Yellow 3 GLH, 0.5 percent Cathilon Red BLH, and 1.4percent Cathilon Red BHH based on the weight of the fibers in theatmosphere.

Note; These names. are the trade name of dyestuffs supplied fromHodogaya Kagaku Kogyo Co. Ltd. After the tow was dyedbypassing through ahigh temperature and high pressure dyeing machine, maintained at 134 C.with saturated steam, it

'. was rinsed, oiled and dried. After that, it was heated under g/m' inweight, under tension between rollers l6, l6 and 17,

17' as in FIG. 1. While passing along on the bottom of guide conduit 14,the crimped tow, 100 mm in width, was enveloped in the wrapping to theextent of 1% times. The wrapped plateshaped tow, drawn out by pinchrollers l7, 17' from the extremityof the guide conduit, was foldeddouble so that the overlapped part. of the wrapping could be envelopedin the center of the fold at the outlet of the conduit. The wrapped towwas then: passed through the equipment as shown in FIG. 2 and was heatedfor one minute at 135 C. under the tension of the wrapping. Theresulting crimps were so stable and permanent that even if the crimpswere straightened at a temperature about 100 C., the fibers recovered tothe original crimped state immediately after relaxing the tension. Thecrimp stability was by far higher than that of a tow which was onlyheated at 100 C. and crimped in a stuffer box. The major part of thecrimps of the heat-set crimped tow of this Example were temporarilyfixed by cooling in a straightened state after the tow was passedthrough a steam chamber at C. It was then cut into staple fibers andspun into yarns. Knitted goods made of the yarns, after steaming,recovered crimps and became articles of high bulk and elegant touch.

EXAMPLE 3 then passed in such a manner that-the overlappedside couldcontact the surface of roller 44; mm in diameter and 150 mm in width, inthe pressurized steam treatment chamber a shown'in FIG. 4. The tow wasrun upward successively from roller 44 to roller 54, and when the towwas returned from roller 54 to roller 53, it was shified aside as muchas 75 mm. It was run again successively downward on these rollers andwas drawn in the air through a narrow pipe having pressure sealingvalves. In this case, the temperature of the saturated steam was C., andthe heat treatment period for the wrapped tow was 45 seconds. Thewrapped tow from the steam chamber was then separated from the wrapping.The tow was further processed, and the wrapping, after removal of thewrinkles and ironing on hot rollers, was-reused as tow wrapping at theinlet side.

Single fibers of the tow thus obtained became 3.5 deniers thick due toheat shrinkage during the heat treatment. The crimps were extremelystably set. The crimps could be easily stretched under tension in hotwater at 100 C., but in a relaxed state after removal of tension, theyrecovered to the original crimped stated.

Excessively stabilized crimps of stable fibers for the use of spinningmaterial interfere with the spinning process, resulting in the fonnationof nap yarns. Therefore, a tow of excessive crimps was passed through asteam chamber of 95C., and after the major part of the crimps werestaretched and temporarily fixed by cooling in the stretched state, thetow was cut into staples. After spinning, weaving or knitting, theproducts were heated in a tension-free state to recover the crimps thatwere fixed at 160 C. Bulky products were obtained.

' EXAMPLE 4 900 polyethylenetelephthate yarns, each of which consistedof 25 filaments of 3 denier and had 100 twists per meter, were dividedinto 3 groups of 300 yarns each after partially warped.

After fixing the arranged order of the warped yarns at both the ends ofeach group by stitching obliquely with threads, the whole yarns lined inparallel were crimped with a stuffer box together with evenlydistributed fine powder of talc to produce crimped yarns in a tow formof 100,000 denier, namely 50 percent excess supply was done.

The whole crimped yams in a tow form were enveloped in a cotton wrappingcloth 300 mm wide and having 35 gram weight per meter (about 300,000denier cloth), travelling under a tension and the wrapped crimped yarnswere introduced into a saturated steam chamber, as shown in FIG. 2,maintained at 160 C. and-subjected the wrapped crimped yarns toheat-treatment for 30 seconds.

Each yarn after heat-treatment became about 100 denier thick due to the30 percent contraction during the heat-treat-' to that of the pressuresealing device) was kept at 12-15 percent and the fiber-density wasraised gradually to percent and then up to 35 percent as the wrappedyarns were heated up by the leaking steam through the sealing device,otherwise the introducing resistance of the wrapped yams through theinlet sealing device became too large.

At the outlet pressure sealing device, the fiber density was keptconstant at 30-35 percent during the heat treatment period of the fibersand the number of valves attached to the device was 3 or 4.

The wrapped yarns after heat-treated were drawn out into the atmosphere,seperated from the wrapping cloth and divided into three originalgroups, each of which was again divided into each single yarn followedby winding on each bobbin.

Advantageously, in this invention the degree of crimping can becontrolled by suitably regulating the apparent deniers of the tow at thetime when the wrapping envelopes the tow. In this way fibers crimped toan extent suitable for proper use can be obtained. of course, if a towof crimped conjugate (composite) fibers is passed through a saturatedsteam chamber, after having been crimped with stuffer box and suppliedin excess to the wrapping according to the method of this invention,such tow is also heated at the softening point of the fibers, that is,at the optimum temperature for annealing. Thus a combination ofmechanically given crimps and conjugate crimps is fixed, or if supply inexcess is slight, the mechanical crimps applied in the stuffer boxmethod vanish and the generated conjugate crimps only are fixed. At anyrate, it is an advantage of this invention that the extent of crimpingis suitably controlled for permanent fixation. This results from heatsetting at the highest possible temperature within the softeningtemperature range, that is, at the annealing point of the fibers, atwhich the strength of the fibers is not lowered to a measurable extent.Of course, since the fibers contract at the annealing point, the crimpswill not remain after the heat treatment, unless a supply in excesscorresponding to the sum of the contraction due to annealing plusapparent contraction due to crimping is done.

I claim:

l. A method for heat-setting of crimps on artificial fibers gathered ina tow form which have been previously crimped by mechanical meanscomprising:

1. enveloping said crimped fibers gathered in a tow form in a wrapping,while the fibers being fed lengthwise in excess to the wrapping so thatthe fibers enveloped in the wrapping can have crimps at least to anextent corresponding to the sum of the predetermined crimping ratio ofthe fibers plus the degree of contraction of fibers at the heat-treatingtemperature thereof,

2. increasing the density of the crimped fibers in the wrapping bymechanical compression,

3. introducing the compressed crimped fibers into and subjecting totravelling through a pressurized zone substantially containing onlysaturated steam at a predetermined temperature selected within the rangeof the heat resistance temperature of the fiber, while guided by theenveloping wrapping which is travelling under a tension,

4. heat-treating the wrapped fibers in said zone while subjecting thefibers to a sufliciently strong lateral pressure from the wrapping,lying on the outer side of the fibers, and travelling under a tension,along larger radii of curveture than that lying inner side of the fiberand travelling in contact with more than one curved surfaces 5.withdrawing the wrapping which envelopes the fibers therein from saidzone and 6. separating the wrapping from the fibers.

2. A method of claim 1, in which the fibers gathered in a tow form is atow consisting of a plurality of individual artificial filaments.

3. A method of claim 1, in which the fibers gathered in a tow form arescores of filament yarns arranged in a tow form.

4. A method of claim 1, in which increase of the density of crimpedfibers in the wrapping is efiected by passing the fibers enveloped inthe wrapping through a tapered conduit.

5. A method of claim 4, in which the supply of the crimped fibers in thewrapping is increased by applying a forward thrust to the crimped fibersat the inlet side of the tapered conduit, thereby forcing the fibersinto the wrapping as it is received by the conduit.

UNITED STATES PATENT OFFECE CERTIFICATE OF CORREC'HGN Patent No.3,667,094 Dated June 6, 1972 Invent0r(s) Masahide Yazawa rs in theabove-identified patent It is certified the 1t error appea by correctedas shown below:

and that said Letters Patent are here Column 7, line 45, "5,000,000"should read 500,000

Signed and sealed this 19th day of December 1972.

(SEAL) Attest:

ROBERT GO'ITSCHALK EDWARD M.FLETCHER,JR.

Commissioner of-Patents Attesting Officer FORM po'wso USCOMM-DC60876-P69 US. GOVERNMENT PRINTING OFFICE 1 1969 386"53.

1. A method for heat-setting of crimps on artificial fibers gathered in a tow form which have been previously crimped by mechanical means comprising:
 1. enveloping said crimped fibers gathered in a tow form in a wrapping, while the fibers being fed lengthwise in excess to the wrapping so that the fibers enveloped in the wrapping can have crimps at least to an extent corresponding to the sum of the predetermined crimping ratio of the fibers plus the degree of contraction of fibers at the heat-treating temperature thereof,
 2. increasing the density of the crimped fibers in the wrapping by mechanical compression,
 3. introducing the compressed crimped fibers into and subjecting to travelling through a pressurized zone substantially containing only saturated steam at a predetermined temperature selected within the range of the heat resistance temperature of the fiber, while guided by the enveloping wrapping which is travelling under a tension,
 4. heat-treating the wrapped fibers in said zone while subjecting the fibers to a sufficiently strong lateral pressure from the wrapping, lying on the outer side of the fibers, and travelling under a tension, along larger radii of curveture than that lying inner side of the fiber and travelling in contact with more than one curved surfaces
 5. withdrawing the wrapping which envelopes the fibers therein from said zone and
 6. separating the wrapping from the fibers.
 2. increasing the density of the crimped fibers in the wrapping by mechanical compression,
 2. A method of claim 1, in which the fibers gathered in a tow form is a tow consisting of a plurality of individual artificial filaments.
 3. A method of claim 1, in which the fibers gathered in a tow form are scores of filament yarns arranged in a tow form.
 3. introducing the compressed crimped fibers into and subjecting to travelling through a pressurized zone substantially containing only saturated steam at a predetermined temperature selected within the range of the heat resistance temperature of the fiber, while guided by the enveloping wrapping which is travelling under a tension,
 4. heat-treating the wrapped fibers in said zone while subjecting the fibers to a sufficiently strong lateral pressure from the wrapping, lying on the outer side of the fibers, and travelling under a tension, along larger radii of curveture than that lying inner side of the fiber and travelling in contact with more than one curved surfaces
 4. A method of claim 1, in which increase of the density of crimped fibers in the wrapping is effected by passing the fibers enveloped in the wrapping through a tapered conduit.
 5. A method of claim 4, in which the supply of the crimped fibers in the wrapping is increased by applying a forward thrust to the crimped fibers at the inlet side of the tapered conduit, thereby forcing the fibers into the wrapping as it is received by the conduit.
 5. withdrawing the wrapping which envelopes the fibers therein from said zone and
 6. separating the wrapping from the fibers. 